Meteorite Impacts Produce Most of Moon

Scientists studying lunar samples brought back by the Apollo missions have determined that the moon’s thin atmosphere is produced largely by meteorite impacts. “Our findings provide a clearer picture of how the moon’s surface and atmosphere interact over long timescales, [and] enhance our understanding of space weathering processes,” said Dr Nicole Nie, the co-author of the new study based at MIT’s department of Earth, atmospheric, and planetary sciences. The Guardian reports: Writing in the journal Science Advances, Nie and her colleagues describe how the lunar atmosphere must be constantly replenished because its atoms are continuously being lost to space, primarily because of the moon’s weak gravity, or trapped on the lunar surface. Ultraviolet photons from the sun can rerelease the latter, but the researchers say replenishment of the atmosphere is thought to rely on atoms being released from within lunar minerals — either via vaporisation by meteorite impacts, or by solar wind sputtering, a process in which charged particles from the sun hit the moon and eject atoms. But which of the two factors dominates had been unclear, with data from Nasa’s lunar atmosphere and dust environment explorer, launched in 2013, suggesting both were at play.